1. Field of the Invention
The invention relates to fuel control systems and, in particular, to a closed loop fuel control system for an internal combustion engine using hydrogen as a fuel.
2. Prior Art
Presently internal combustion engines use fossil or hydrocarbon type fuels. The world supply of fossil fuels, as we know, is limited and already the scientific community is looking at alternatives to the hydrocarbon fuels. Added to this, ecological problems stemming from the widespread use of hydrocarbon fuels is hastening the development of alternate relatively pollution-free alternates. One of the primary candidates as an alternate fuel is hydrogen, which is in abundant supply, and its by-product of combustion is water, which is not considered as a pollutant. Considerable research using hydrogen as a fuel is underway and operative engines using hydrogen as a fuel have been built and tested. The use of hydrogen as a fuel is taught by Billings in U.S. Pat. No. 3,983,882 (October 1976). This concept was also taught by A. F. Bush and W. D. Van Vorst in a paper presented at the Cryogenic Conference, Aug. 8-10, 1973 from Advances in Cryogenic Engineering Underwood in U.S. Pat. No. 3,862,624 (January 1975) and Smith in U.S. Pat. No. 3,608,529 (September 1971) also teach the use of hydrogen as a fuel. The hydrogen fuelled engine systems taught by the prior art cited above are open loop systems and must be periodically adjusted to assure optimum performance and optimum fuel economy.
The more advanced electronically controlled fossil fuel systems are tending towards closed loop systems in which the oxygen content of the exhaust is continuously monitored to provide a correction to the quantity of fuel being delivered to the engine to compensate for degradation, wear, or other changes in the engine's fuel/air delivery system, as well as for subtle changes in the operating characteristics of the engine. A typical example of one such closed loop electronically controlled fossil fuel system is taught by Seitz in U.S. Pat. No. 3,815,561 (June 1974).
The present invention is a closed loop electronic control system for a hydrogen fuelled engine using a sensor detecting the quantity of unburned hydrogen in the engine's exhaust.